22 January 2019

New ‘architecture’ discovered in corn

LSU’s Tuo Wang and colleagues discovered that lignin has limited contact with cellulose inside a plant. Instead, the wiry complex carbohydrate called xylan connects cellulose and lignin as the glue. LSU’s Tuo Wang and colleagues discovered that lignin has limited contact with cellulose inside a plant. Instead, the wiry complex carbohydrate called xylan connects cellulose and lignin as the glue. Tuo Wang, LSU

Findings that “go against the textbooks” may improve biofuel production

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BATON ROUGE — New research on the most economically important agricultural plant in the U.S. — corn — has revealed a different internal structure of the plant than previously thought. The surprising discovery, made with the help of powerful magnets at the National High Magnetic Field Laboratory (National MagLab), could help optimize how corn is converted into ethanol.

“Our economy relies on ethanol, so it’s fascinating that we haven’t had a full and more precise understanding of the molecular structure of corn until now,” said Tuo Wang, an assistant professor of chemistry at Louisiana State University who led this study, published this week in Nature Communications. “Currently, almost all gasoline contains about 10 percent ethanol. One-third of all corn production in the U.S., which is about 5 billion bushels annually, is used for ethanol production. Even if we can finally improve ethanol production efficiency by 1 or 2 percent, it could provide a significant benefit to society.”

Wang and colleagues are the first to investigate an intact corn plant stalk at the atomic level using high-resolution techniques. The team includes postdoctoral researcher Xue Kang and graduate students Malitha Dickwella Widanage and Alex Kirui, all of LSU, as well as Fred Mentink-Vigier, a physical chemist at the National MagLab. Mentink-Vigier runs the magic angle spinning dynamic nuclear polarization (MAS DNP) program in the lab’s Nuclear Magnetic Resonance (NMR) Facility, and provided technical expertise for Wang’s challenging experiment.

“Because lignin made up only a fraction of the sample, its NMR signal was very weak,” explained Mentink-Vigier said. “But thanks to the combination of the MAS DNP and the microwave setup developed here at the MagLab, we were able to boost and isolate those signals."

Tuo WangTuo Wang (left) and Fred Mentink-Vigier at the National MagLab's MAS DNP system.
Credit: Stephen Bilenky
It has been previously thought that cellulose, a thick and rigid complex carbohydrate that acts like a scaffold in corn and other plants, connected directly to a waterproof polymer called lignin. However, Wang and colleagues discovered that lignin has limited contact with cellulose inside a plant. Instead, the wiry complex carbohydrate called xylan connects cellulose and lignin as the glue.

It has also been previously thought that the cellulose, lignin and xylan molecules are mixed, but the scientists discovered that they each have separate domains and these domains perform separate functions.

“I was surprised. Our findings actually go against the textbook,” Wang said.

With its waterproof properties, lignin is a key structural component in plants. It also poses a challenge to ethanol production because it prevents sugar from being converted to ethanol within a plant. Significant research has been done on how to break down plant structure or breeding more digestible plants to produce ethanol or other biofuels. However, this research has been done without the full picture of plants’ molecular structure.

“A lot of work in ethanol production methods may need further optimization, but it opens doors for new opportunities to improve the way we process this valuable product,” Wang said.

This means a better enzyme or chemical can be designed to more efficiently break down the core of a plant’s biomass. These new approaches also can be applied to biomasses in other plants and organisms as well.

In addition to corn, Wang and his colleagues analyzed three other plant species: rice, switchgrass (also used for biofuel production) and the model plant species Arabidopsis, which is related to cabbage. The scientists found that the molecular structures of the four plants are similar.

They discovered this by using NMR spectroscopy instruments at LSU and the National MagLab. Previous studies that used microscopes or chemical analyses have not shown the atomic-level structure of the native, intact plant cell architecture. Wang and his colleagues are the first to directly measure the molecular structure of these intact plants.

They are now analyzing wood from eucalyptus, poplar and spruce, which could help improve the paper production and material development industries as well.

— Story courtesy of Louisiana State University


The National High Magnetic Field Laboratory is the world’s largest and highest-powered magnet facility. Located at Florida State University, the University of Florida and Los Alamos National Laboratory, the interdisciplinary National MagLab hosts scientists from around the world to perform basic research in high magnetic fields, advancing our understanding of materials, energy and life. The lab is funded by the National Science Foundation (DMR-1644779) and the state of Florida. For more information, visit us online at nationalmaglab.org or follow us on Facebook, Twitter, Instagram and Pinterest at NationalMagLab.